Molecular Latitude

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Science  14 Mar 2003:
Vol. 299, Issue 5613, pp. 1627
DOI: 10.1126/science.299.5613.1627d

Most groups of organisms obey latitudinal gradients in species richness, whereby numbers of species increase from the poles toward the equator. The reasons for these gradients remain contentious. One proposal is that increased temperature and solar radiation lead to faster growth, shorter generation times, elevated mutation, and faster molecular evolution, all of which should combine to produce more rapid rates of speciation. Bromham and Cardillo investigated this proposal using a comparative test of the rates of molecular evolution of mitochondrial and nuclear DNA in phylogenetically independent pairs of bird species from different latitudes. The phylogenies reconstructed from the sequence data indicated no statistically significant differences between rates of molecular evolution at different latitudes, arguing against the proposal that climatic factors directly influence the speciation rate in birds. — AMS

J. Evol. Biol.16, 200 (2003).

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